Hi all,

I am trying to setup voltage measurement on my ArduPilot Mega / Shield board.
However I am really confused about the resistor I have to install.

On the manual it says that I have to solder a 3.9K resistor for each cell I want to measure.
Since I want to measure a 3S battery pack, I soldered the 3 resistor that came with my board.

However the voltages shown aren't right.
The command line shows the following when connecting a fully charged battery:

test] battery
Volts: 1:3.82, 2:7.74, 3:11.60, 4:11.47

The same battery shows 12.5V when connected to a separate voltage meter.

What confuses me are the colors of the resistor.
On the picture of the manual, the colors seems to be yellow, violet and brown which I think it is 470.
The resistor that came with the board are colored orange, gray and brown which is 380.
And the colors that I think should be right are: orange, white and red which is 3.9K.

Could you please help me out on what resistors I should install, and how many of them?

Thank you very much.


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This may help:



parameters are in config.h


// Battery monitoring



# define VOLT_DIV_RATIO             3.56






# define INPUT_VOLTAGE              5.0



You're reading your color codes wrong. The ones that come with the IMU are orange, white, black, brown, which is 390x10 or 3.9k, exactly as described in the product listing.
Thanks Chris.

Thank you Michael.  I think the link to the discussion will be very helpfull.

I will try tonight.



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